Posted by: Ryan | August 21, 2008

Photons

Daisy

Thought experiment:

  1. Imagine a photon. Without mass, it travels constantly at the speed of light, does not age, and has wave-particle duality. Interesting little guys.
  2. All we see is made of photons. As you sit in a field of flowers, the lavender petals and green stems, all colors and shapes — composed entirely of photons; tons of them. Brightness is dictated by the amount of photons reaching your retina. Color is determined by their wavelength.
  3. Think of what incredible amount of these tiny wave-particles it must take to sculpt a typical human vision. Perhaps a mountain landscape on a sunny day, with green hills, billowing clouds, golden aspens by a rushing creek. Perhaps reading a good book on a park bench, the dark ink, the fine texture of the paper, the small hairs on the skin of your arms holding it. Or getting off the bus to work, the cracks in the sidewalk, neon signs, taxis, people passing in suits and summer dresses and faded blue jeans.
  4. Each of these sights can be captured on film. A digital camera will capture all those photons for eternity. Imagine how many pictures you can take of that lavender flower. From the left, from the right, from the middle? High-angle, mid-angle, or low? Photons from the sun bounce off in every direction, enough for us to take pictures of a flower in any fashion we please. In other words, a huge number of photons just hit that flower.
  5. Imagine many other flowers. A field. A wide meadow. A mountain ridge. A national forest. Your state. Nation. Continent. The Earth.
  6. All these photons (or, well, most of them) came from our sun, flying through space for about eight minutes before ricocheting through our blue atmosphere and eventually bouncing off the flower petal and into your eye/camera.
  7. Imagine what small percentage of the sun’s total radiance is intercepted by the Earth. The incredibly vast majority of its photons disperse into interstellar space. These are lost forever to our eyes, to my digital camera.
  8. How many photons does that make? In only one moment in time, for a star that has already been shining for over four billion years, and will continue for many more.

I find it refreshing to reflect sometimes on the enormity of our universe, and our small (yet important) existences on it.

No wonder that one of my favorite quotes is this: “The Sun, with all the planets revolving around it, and dependent upon it, can still ripen a bunch of grapes as if it had nothing else in the universe to do.” (Galileo).

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Responses

  1. nice!

  2. Of all the things to be into… I’m into photons. This is my favorite photon article ever. Thanks.


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